Who knows twenty-three?
Please cite/link your sources, if possible. After about one business day, I will:
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23 cubits (and a fraction) is the difference in elevation between the Spring of Eitam and the courtyard of the Beis Hamikdash.
The importance of this is that this spring was the source for the Kohen Gadol's mikvah, which was situated atop one of the gates (twenty cubits above the courtyard) and which was three cubits tall. In this way the water could flow into the mikvah based on gravity alone, without requiring pumps or the like, which would disqualify it. (Yoma 31a)
23 are the judges of a Sanhedrin. (Notice I said "a Sanhedrin" meaning the smallest Beis Din that can apply death penalties as opposed to the Great Sanhedrin that sat in the "Hewn Chamber" in the Beis Hamikdash.) (Sanhedrin, 2ab)
23 are the years that Avraham and Sarah spent proselytizing in Charan.
[They started in the year 2000 since Creation, when Avraham was 52 (Avodah Zarah 9a), and they left Charan permanently when Avraham was 75 (Gen. 12:4).]
Twenty-three are the books of Tanach that the Talmud says are definitely non-fiction.
(Iyov/Job being the odd man out, one opinion in the Talmud (Bava Basra 15a) is that he never existed.)
23 are the days from Rosh Hashanah to Simchas Torah outside of the Land of Israel.